"Milorganite" as a source of minor nutrient elements for plants

The availabilities of the minor nutrient elements in and their influence on plant growth were studied by growing corn, tomatoes, and sunflowers in nutrient solutions, some of which were supplied with carbonated water extract of Milorganite as the only source of boron, copper, manganese, molybdenum, and zinc. The tomato and sunflower plants were analyzed for each of these elements, except molybdenum, and corn for each except boron and molybdenum. obtained may be summarized as follows: Corn made very little growth and exhibited typical deficiency symptoms in solution cultures from which either manganese or zinc was omitted, while a fairly large but abnormal growth resulted where copper was omitted. The addition of Milorganite extract to some of these cultures during the last 2 weeks of the 7-week growth period resulted in the resumption of normal growth in each instance. Milorganite extract increased the yield in all cases except in controls which were already supplied with all nutrients. Increases in the amounts of copper, manganese, and zinc absorbed by the plants were noticed wherever the extract was supplied. Tomato and sunflower plants made good growth in every culture where Milorganite extract served as the only source of one or more of the minor elements. Inferior growth, exhibiting deficiency symptoms, was generally observed in the series of duplicate cultures which did not receive the extract or other sources of these elements. In all cultures that received it, except controls, Milorganite extract significantly increased the dry weights of the plants and the contents of boron, copper, manganese, and zinc. The results of the investigation show clearly that Milorganite when used as a fertilizer or as a constituent of mixed fertilizer may serve as a source of the minor nutrient elements for plant growth.